Activity For Decomposition Of Acetaldehyde Research Articles

Dependence of photocatalytic activity on aspect ratio of a brookite TiO2 nanorod and drastic improvement in visible light responsibility of a brookite TiO2 nanorod by site-selective modification of Fe3+ on exposed faces

Exposed crystal face-controlled brookite titanium(IV) oxide (TiO2) nanorods with various aspect ratios were prepared by a hydrothermal process with or without PVA or PVP as an aspect reagent. The nanorod-shaped brookite TiO2 had larger {210} and smaller {212} exposed crystal faces, which were assigned by TEM with the SAED technique. Their aspect ratios were greatly influenced by the addition of PVA or PVP as an aspect ratio control reagent to the reaction solution used in the hydrothermal treatment. The photocatalytic activity for decomposition of acetaldehyde increased with increase in the aspect ratio because the surface area ratio of {210} to {212} exposed crystal faces, which are attributed to reduction and oxidation sites, respectively, became more optimal.The {212} exposed crystal faces of surface-controlled brookite TiO2 were site-selectively modified with trivalent iron(III) (Fe3+) ions by utilizing the adsorption property of iron(III)/iron(II) (Fe3+/Fe2+) ions. The brookite TiO2 nanorod with site-selective modification of Fe3+ ions showed much higher photocatalytic activity than that of commercial brookite TiO2 loaded with Fe ions under visible-light irradiation because of the separation of redox sites. In other words, oxidation and reduction proceed over Fe3+ ion-modified {212} faces of the TiO2 surface and on {210} faces of the TiO2 surface without modification of Fe3+, respectively.

Improvement of photocatalytic activity of high specific surface area graphitic carbon nitride by loading a co-catalyst

Graphitic carbon nitride (g-C3N4) was synthesized by heating melamine and was then treated with sodium hydroxide solution under a hydrothermal condition to obtain g-C3N4 with a large specific surface area (HSSA). HSSA shows higher photocatalytic activity for decomposition of acetaldehyde than that of original g-C3N4. HSSA was modified with RuO2 as a co-catalyst by the impregnation method. HSSA loaded with 0.05 wt% RuO2 shows the highest photocatalytic activity for acetaldehyde decomposition under visible light (λ = 455 nm).

Complete oxidation of acetaldehyde over a composite photocatalyst of graphitic carbon nitride and tungsten(VI) oxide under visible-light irradiation

Graphitic carbon nitride (g-C3N4) was prepared by heating melamine and then its specific surface area was enlarged by hydrothermal treatment in aqueous sodium hydroxide solution. The g-C3N4 samples were blended with tungsten(VI) oxide (WO3) using a planetary mill in order to improve photocatalytic activity. The composite photocatalyst with optimized amounts of these contents showed higher photocatalytic activity for decomposition of acetaldehyde under visible-light irradiation than did original samples. From the results, we concluded that the composite photocatalyst utilizes both high oxidation ability of WO3 and high reduction ability of g-C3N4 by Z-scheme charge transfer.

New pathway to prepare gold nanoparticles and their applications in catalysis and surface-enhanced Raman scattering

As shown in the literature, additional energies are necessary for the reduction of positively charged noble metal ions to prepare metal nanoparticles (NPs). In this work, we report a new green pathway to prepare Au NPs in neutral 0.1M NaCl aqueous solutions from bulk Au substrates without addition of any stabilizer and reductant just via aid of natural chitosan (Ch) at room temperature. Au- and Ch-containing complexes in aqueous solution were electrochemically prepared. The role of Ch is just an intermediate to perform electron transfer with Au NPs. The stability of these prepared Au NPs is well maintained by Au NPs themselves with slightly positively charged Au remained on the surface of Au NPs. The particle size of prepared spherical Au (111) NPs is ca. 15nm in diameter. Moreover, increasing the pH of preparation solutions can be contributive to preparing concentrated Au NPs in solutions. The prepared Au NPs are surface-enhanced Raman scattering (SERS)-active for probe molecules of Rhodamine 6G. They also demonstrate significantly catalytic activity for decomposition of acetaldehyde in rice wine.

Dependence of Photocatalytic Activity on Aspect Ratio of Shape-Controlled Rutile Titanium(IV) Oxide Nanorods

Shape-controlled rutile titanium(IV) oxide (TiO2) nanorods with various aspect ratios were prepared by two-step synthesis in the presence of two kinds of inorganic anions. The first synthesis step from titanium(III) chloride solution induced the formation of aggregated needlelike rutile TiO2, the shape of which largely depended on the inorganic anion used. Moreover, shape-controlled rutile TiO2 rods with {110} side crystal faces and {111} and/or {001} edge crystal faces were obtained by hydrothermal treatment of the needlelike rutile TiO2. Their aspect ratios were largely influenced by the starting material used in the hydrothermal treatment. The photocatalytic activity for decomposition of acetaldehyde increased with decreasing aspect ratio because the surface area ratio of {111} and/or {001} to {110} exposed crystal faces, which are attributed to oxidation and reduction sites respectively, became more optimal.

Synthesis of Au nanoparticles supported on metal oxides (H3PMo12O40 and TiO2) by PS-PVP block copolymer encapsulation method

Au supported on metal oxides (P-25, HPA) was successfully synthesized by PS-PVP block copolymer encapsulation method. The size of nanoparticles was strongly dependent on calcination conditions (time and temperature). The particle size was also controlled by selection of the appropriate length of PVP part in block copolymer. When particulate gold was doped on the surface of P-25, it strongly improved visible light absorption by plasma resonance. Compared with pure TiO2, Au supported on P-25 demonstrated much higher photocatalytic activity for acetaldehyde decomposition under visible light illumination. The enhanced photocatalytic activity could be attributed to the increase of visible light absorption and catalytic activity of nanoparticulate Au.

Visible-Light-Induced Hydrophilic Conversion of an S-Doped TiO2 Thin Film and Its Photocatalytic Activity for Decomposition of Acetaldehyde in Gas Phase

S-doped titanium dioxide thin films were found to undergo hydrophilic conversion under visible light irradiation. The water contact angle for the S-doped TiO2 thin film reached to 15° under visible light irradiation. The photocatalyzed decomposition of acetaldehyde (ALD) in gas phase on TiO2 thin films was investigated in a batch-type photocatalytic reactor. The photocatalytic activities of TiO2 thin films for decomposition of ALD were investigated by analyzing amount of ALD consumed and CO2 generated under visible light irradiation at wavelengths longer than 420 nm.

Enhanced Visible Light Sensitivity of Nitrogen-doped Nanocrystalline Si-modified Titania Prepared by the Glycothermal Method

Abstract Nanocrystalline silica-modified titania prepared by the thermal reaction of titanium tetraisopropoxide and tetraethyl orthosilicate in 1,4-butanediol was treated in an NH3 flow at high temperatures. The thus-obtained nitrogen-doped silica-modified titania showed a strong absorption in the visible region (400–500 nm) and exhibited a high photocatalytic activity for decomposition of acetaldehyde under visible light irradiation.